Mil
Conversion Chart

This converter features contemporary units of length. There is also a special converter for historical units of length you might want to visit for ancient, medieval and other old units that are no longer used.

The American System of Measures (US Customary Units)

American weight and measures are based on units used in Britain prior to 1824, when imperial system was officially established. The US law of 1866 set a relationship with the metric system by defining the meter as equal to 39.37 in. Since then all measures were redefined in terms of metric units with the last minimal adjustment in 1959. However the old standard of 1ft was retained with the name US survey foot.

British (Imperial) Measure

The first English official measurement standards were defined in 15th century. British system of units, known as imperial units, was established in 1824. Later in 1963 the standards were redefined in terms of metre stantard maintained in Paris. From 1995 the UK adopted metric units for general use. The only imperial measures of length that can be officially used now are miles, yards, feet and inches for road traffic signs.

International Nautical Measure

The international nautical mile was defined by the First International Extraordinary Hydrographic Conference, Monaco in 1929. This is the only definition in widespread current use, and is the one accepted by the International Bureau of Weights and Measures. Before 1929 different countries had different definitions, and the Soviet Union, the United Kingdom and the United States did not immediately accept the international value.

Optical

Geographical (German)

Computer Equipment

A rack unit, U or RU is a unit of measure that describes the height of equipment designed to mount in a 19-inch rack or a 23-inch rack. The 19-inch (482.6 mm) or 23-inch (584.2 mm) dimension refers to the width of the equipment mounting frame in the rack including the frame; the width of the equipment that can be mounted inside the rack is less.

Astronomical

Grace Hopper's units of distance

Grace Hopper is famous for her nanoseconds visual aid. People used to ask her why satellite communication took so long. She started handing out pieces of wire that were just under one foot long (11.80 inches) — the distance that light travels in one nanosecond. She also passed out packets of pepper, calling the individual grains of ground pepper picoseconds. She also used these aids to illustrate why computers had to be small to be fast.

Natural units

In physics, natural units are physical units of measurement based only on universal physical constants. The origin of their definition comes only from properties of nature and not from any human construct.

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